Read full in PDF. - Blog. Ventilation systems

WWW.VENTILATION-SYSTEM.COM
HYDROPONICS
VENTILATION BASICS
Importance of ventilation and environmental control in a grow room
Air movement, namely air supply and exhaust, is one of the most important
aspects of any hydroponics installation which is often overlooked.
Correctly ventilating your growing area is a vital part of greenhouse or
grow room design. Adequate ventilation in the grow room is important for
a number of reasons – temperature, humidity, disease and odour control,
and fresh/stale air exchange.
The plants in any hydroponically grown crop will absorb the available CO2
in a very short amount of time. Therefore, it is very important to supply
fresh air to the plants to keep the CO2 level from becoming too low and
diminishing the crop yield. Low levels of CO2 means slow growth and small
yields.
As well as increasing CO2 nourishment level, the continuous supply and
exhaust of air significantly reduces the chances of any disease to develop
within a given greenhouse.
Regular air circulation
provides constant grow
Diseases usually thrive and develop within environments where the air
is still and humid. A humid, still environment allows disease to enter the
plants through the build up of moisture on the leaves due to poor airflow
and a lack of fresh air. If this is not controlled properly, the plants are likely
to fail.
Fresh air supply increases the amount of CO2 which is needed for all plants
to survive. CO2 makes up approximately 50% of the dry weight of the
plant, and oxygen makes up the rest 42%.
Plants require CO2
to grow healthy
Negative impact
due to lack of CO2
Still and humid air puts
plants to death...
Note! However, this problem can be eliminated with the
regulation of humidity levels using VENTS humidity sensors
and temperature regulators which work in conjunction with all
VENTS fans (see page 28-29).
Besides exhaust and supply of air within any greenhouse, good air
circulation throughout the growing area is extremely important to
minimize the potential damage caused by insects. One way to minimize
insect damage is to install fixed or oscillating air circulation fan. This
fan provides a continuous stream of air over the growing area making it
difficult for insects to settle and damage the plants.
In summary, an efficient hydroponics air movement system will provide
vital plant CO2 nourishment, develop a strong healthy root system which
enables the efficient supply of water and nutrients and minimize the
damage caused by disease and insects.
1
Setting up your greenhouse
The calculations that are used to correctly design a ventilation system can
be quite complex and require numerous known variables.
So, you have decided to deal with indoor gardening. Before you start we
would like to tell you some basic rules you have to be aware of.
Here’s VENTS’ guide to setting up a basic, properly ventilated indoor
garden on a budget.
The purpose of this brochure is to simplify these calculations while helping
you to set up a greenhouse and to better understand ventilation in it.
As soon as you selected where you are going to set up your indoor garden
it’s time to spec out exactly what you will need to make it all happen.
This brochure shows the ventilation requirements for 2 lights grow room
that are most commonly used.
Big rooms need lots of lights with a high-powered ventilation system
whereas small rooms will only need a few lights with a low powered
ventilation system. All sounds rather simple. But you should work out what
exactly your room needs. Here’s what you need to consider:
The design, selection and installation of any hydroponics ventilation
system is therefore the top priority to ensure the healthiest and highest
quality crop yields.
2
WWW.VENTILATION-SYSTEM.COM
Step 1: grow room size calculation
So, the first thing you need to do is accurately measure it – calculate the
total volume of the greenhouse in cubic meters. You will need the length,
width and height of the grow room. Use the simple formula:
Height, m
Recommended distance between the light and the canopy that most
growers follow are:
1
600 W
80 - 100 cm
400 W
60 - 80 cm
0,5
40 - 60 cm
1000 W
Length x Width x Height = Volume of the greenhouse (m3)
A x B x H = V (m3)
0
400
600
1000
Light power, W
Note! Bear in mind that the above information is for horizontally
mounted lamps in normal open or closed reflectors. If you are
using parabolic reflectors with vertically mounted lamps or aircooled reflectors you can allow the light to be closer to the plants
as there is less direct radiant heat.
A
The most commonly used light sizes for indoor growing are 1000 W, 600 W
and 400 W. Each size light is suitable for a defined amount of floor space:
H
B
Fig. 1
1000 W
600 W
As an example, your greenhouse has the following dimensions: length
(A) – 3,65 m, width (B) – 2,4 m, height (H) – 2,5 m (Fig. 1).
V, m3
=
3,65 x 2,4 x 2,5
=
21,9 m3
By the way, the more insulated your grow room - the better. A well insulated
room will immediately lend itself to far easier environmental control.
Step 2: lighting equipment selection
Now you know the size of the room you’re working with and can calculate
how best to illuminate it. Your mission is to provide your plants with all the
light they need to grow and bloom, but you need to maintain your indoor
garden’s environment so that it is optimal for plant metabolism.
1,2 - 1,55 m
1 - 1,2 m
400 W
0,75 - 1 m
So the floor space available in the room is 3,65 m x 2,4 m. You could try and
squeeze as many lights as possible into this room, but as well as being productive, you want to try and make your room easy and comfortable to work
in. To do this you will need adequate access around your plants to make
maintenance and inspections easy.
Approximately 0,66 m around your plants is a good working area (Fig. 2).
Note! Important thing to bear in mind is that the more powerful
the light, the further away from the tops of the plants it should be.
COR
REC
T !!
!
HIG
TOO
min 66 cm
ALL
TO
O
LO
W
!
H!
This means that if you have a low ceiling height, you should consider using
lower wattage lights. The example room has an 2,5 m ceiling height so we
can use the 600 W lights, as long as the plants don’t get bigger than 1,5
m. Indoor plants want to be short and wide to take the most of the light
available.
Fig. 2. Minimal distance between plants must be not less then 0,66 m.
3
1,2 m
0,6 m
Experienced growers may select considerably more space than this. In our
example we’re using 2 x 600 W lights (Fig. 3).
3,65 m
1,2 m
min
0,66 m
0,6 m
600 W
600 W
0,6 m
•
0,6 m
min
0,66 m
0,6 m
3,65 m
600 W
0,6 m
600mW
2,4
0,6 m
0,6 m
Fig. 3. Grow room plan with 2x600 W2,4lamps.
Grow room size is 2,4 x 3, 65 m.
m
If you want to make life difficult for yourself, you could fit a maximum of
2,4 m
6 x 600 W lights (Fig. 4).
600 W
How to calculate size and air capacity of exhaust fan
First of all, you need to find out what size of exhaust fan is needed. There
are many ways to calculate the size of exhaust needed for a particular sized
room, some formulas are more accurate, others are overly complicated –
the following method is very popular and has served many growers well:
Required exhaust
fan air capacity
(m3/h)
600 W
=
Volume of active
growing area (m3) x
air changes per time
unit (hour)
x
Carbon
filter loses
rate
2,4 m
Note! When we say the volume of the active growing area, we
600 W
600 W
3,65 m
1,2 m
600 W
600 W
600 W
600 W
3,65 m
mean the volume occupied by the lights and plants.
600 W
600 W
1,2 m
1,2 m
600 W
600 W
1,2 m
Fig. 4. Grow room plan with 6x600 W lamps. Grow room size is 2,4 x 3, 65 m.
In order to make this room work you would need to choose a growing
system or technique that allows you to move the plants to gain access
around the garden. This might be achieved by growing in pots/containers
or movable beds.
Step 3: ventilation equipment selection
Ventilation in your grow room comprises of two main factors: the removal of hot waste (CO2 depleted) air and the input of fresh cooler air.
Hot waste air is removed actively using an inline centrifugal fan VENTS VK
series (the exhaust fan). Fresh cooler air can either be drawn in passive
ventilation way (through vent-holes) or pushed in actively using an inline
mixed-flow fan VENTS TT series (the intake fan), which you as well can
use as an extractor.
Knowing the size of the room and the amount if light being used, you can
work out the ventilation requirements rated in cubic meters per hour (m3/h).
4
To work out the volume simply multiply the length x width x height. In our
example with 2 x 600 W lights this is 1,2 m x 2,4 m x 2,5 m, which gives the
volume of the active growing area of 7,2 cubic meter.
Once you have your volume, you need to multiply it by the amount of air
changes needed per unit of time.
Note! For the majority of indoor gardens without air
conditioning or supplementary CO2, the rule of thumb is one air
change per minute.
So you need to multiply the volume of active growing area by 60 to
calculate the amount of air changes needed per hour.
Finally, when using a carbon filter attached to the exhaust fan, expect
a drop in fan efficiency by approximately 25%. This figure is not fixed
and depends on the make and age of the filter, the length and course of
ducting between the fan and filter and many other factors. To step up this
efficiency drop of 25% - simply multiply by 1,25.
Note!
Using a carbon filter drops in fan efficiency by
approximately 25%.
WWW.VENTILATION-SYSTEM.COM
If we run this equation through our grow room example, it gives us:
Required exhaust fan
air capacity (m3/h)
Required exhaust fan air
capacity (m3/h)
=
Volume of Active Growing
Area (m3) x 60
=
x 1,25
If the garden is located in a very sun-exposed location, such as an upstairs
bedroom or attic, then the exhaust fan size may need to be increased by
approximately 25% (Fig. 6).
((1,2 x 2,4 x 2,5) x 60) x 1,25
Exhaust fan:
calculated
air capacity
+ 25%
=
540 m3/h
Bear in mind that for
the grow room
placed in sun-exposed
location you need
to increase calculated
exhaust fan size and
air capacity by app. 25%
This final figure is the minimum size of exhaust fan needed.
600 W
IN RESULT
Exhaust fan: VENTS VK 200
Pipe diameter: 200 mm
Air capacity: 540 m3/h
Fig. 6. Grow room located in bedroom or attic.
More often than not, you will have to match your required exhaust fan
size to the nearest size available. In this instance the nearest widely available fan size is a 200 mm 780 m3/h VENTS VK 200 inline centrifugal exhaust fan.
•
600 W
How to calculate size and air capacity of intake fan
As mentioned above, your greenhouse must be ensured with continuous
supply of fresh air from outside the growing area. This can be achieved in
2 ways:
First way:
Making passive ventilation (basically vent-holes) through which fresh air
can be drawn in (through the open window)(Fig. 7).
If the grow room is in a very well insulted location, such as a basement
(Fig. 5), using this figure should be fine.
carbon
filter
carbon
filter
exhaust fan
VENTS VK
flexible air duct
rectangular
ventilation grille
open
window
TM / T
j
grow r
Fig. 7. Passive ventilation.
For the grow room
placed in insulated
location the above
mentioned calculation
is fine.
Fig. 5. Grow room located in basement.
Note! As a rule, the passive vent-holes should be 2 to 3 times the
diameter of the exhaust fan outlet.
This means that if the extractor has 150 mm diameter, the grow room will
need 2-3 x 150 mm vent-holes or rectangular ventilation grilles with equal
surface area. When installing passive ventilation, always have the exhaust
fan at the opposite end of the grow room.
5
Second way:
Installing active inline fans that push fresh air into the greenhouse, which
run more efficiently than passive vent-holes (Fig. 8).
VENTS KOM spring-loaded backdraft damper series that opens when the
fan turns on and closes when it turns off. This system gets installed in-line
with VENTS Polyvent series or VENTS Isovent series flexible air ducting
(Fig. 11).
carbon
filter
flexible air duct
exhaust fan
VENTS VK
open
window
intake fan VENTS TT
backdraft dampers
TM / TMY
joint
grow room
flexible duct
By pushing in fresh air you’re not putting much strain on the extractor fan
and you also cancarbon
choose where to pullflexible
the fresh
air from.
air duct
filter
During the cooler winterexhaust
months
better
fan its
VENTS
VK not to pump in very cold air,
but to pull slightly warmer air from inside your home (bedroom or living
room), which is benefited being slightly higher in CO2 (Fig. 9).
exhaust fan
VENTS VK
flexible air duct
intake fan
VENTS TT
filter box
FB
TM
joint
flexible air duct
oscillating fan
bedroom
х
damper
KR
TM / TMY damper
joint
KR
Fig. 9. Fresh air source in winter time.
Fig. 11. Accessories (see page 30-31).
Note! When installing an intake fan make sure it’s supplying in
less air than is being removed by the extractor.
To find out the intake fan diameter you will need to take the exhaust fan
size and apply an estimated reduction for the carbon filter - 25%. If our
target for the intake fan is 15% less air than the exhaust we need to multiply the reduced output by 0,85. Below is a pattern through of how to size
up the intake fan for the example room with 2 x 600 W lights.
Extractor VENTS VK 200 air capacity – 780 m3/h
During the summer months its best to pull fresh cooler air in directly from
outside as air from inside your house is likely to be warmer (Fig. 10).
carbon
filter
flexible air duct
exhaust fan
VENTS VK
insulated flexible duct
This creates a “negative pressure”, ensures that all the air gets out through
the carbon filter and does not strain both exhaust and intake fans. If you
input more air than the exhaust fan can remove, the air will start to build
up and cause a “positive pressure” forcing untreated air out of the grow
room. So when selecting an intake fan it should have a maximum air flow
capacity that is 10-20% lower than the actual output of the exhaust fan.
oscillating fan
carbon
filter
intake fan
VENTS TT
TM / TMY
joint
grow room
filter box FBV
bedroom
Fig. 8. Active ventilation.
TM / TMY
joint
grow room
filter box FB
flexible air duct filter box FB
flexible air duct
bedroom
filter box
FB
damper
KR
TM
joint
х
damper
KR
Estimated extractor air capacity
with carbon filter
Intake fan air
capacity (with
reduction to
ensure negative
pressure)
=
Extractor
air capacity
x
0,75
=
585 m3/h
=
Estimated
extractor
air capacity
with carbon filter
x
0,85
=
497 m3/h
For this intake air capacity the nearest widely available fan size is a 150 mm
VENTS TT 150 fan or a 150 mm VENTS VK 150 fan.
Note! Installing the intake fan, make sure the exhaust fan is at
the opposite end of the grow room.
Fig. 10. Fresh air source in summer time.
Whenever you pull air straight from outside it’s best to use an intake panel
filter boxes (“bug screens”) VENTS FB series (with flat filtering element) or
VENTS FBV series (with V-filtering element, increased filtering area) to
limit the possibility of sucking in pests. To prevent back draft of air use
6
It’s better to split the intake air with a solid VENTS TM or TMY round duct
fittings so that the cooler fresh air is distributed evenly. Also take into account that inline mixed-flow fans Vents TT series are better at pushing
than pulling air through ducting or a carbon filter (Fig. 12).
TM / TMY
joint
grow room
flexible air duct filter box FB
bedroom
WWW.VENTILATION-SYSTEM.COM
carbon
filter
flexible air duct
exhaust fan VENTS VK
2. Certain types of crop can cause bad odour. A professional carbon filter
attached to the exhaust fan will help you to achieve 90-95% odour removal, meaning that just about any crop can be grown without comment.
However, it’s important to match the correct filter to your fan (Fig.14);
odours have a measurable “dwell” time that needs to be met before they
are completely absorbed. Therefore, a 750 m3 capacity exhaust fan will
oscillating fan
need a 750 m3 carbon filter. Don’t try to use a lower capacity filter, it won’t
work!
VENTS
VENTS
oscillating fan
TM / TMY
joint
Fig. 14. Carbon filter absorbs any kind of bad odour caused by plants and
some crops types. Extracted air stay filtered and odourless.
Fig. 12. Air distribution.
This means that when positioning your intake fan, it’s better to place it
nearer the source of fresh air and push it towards the grow room. To make
the air reach the greenhouse efficiently, make sure the flexible air duct is
smooth and straight.
Usefull advices to improve ventilation in your grow room
1. Position your intake fan low down, diagonally opposite the exhaust. Remember, you should mount your exhaust fan high up (Fig. 13). This will
allow a fresh current of cool air to flow across your grow room, whilst
removing any hot, humid air at the same time. When mounting your intake
and exhaust fans, use the proper brackets to avoid vibration (VENTS TT
and VENTS VK fans series are supplied with mounting brackets). You may
also use fan holders VENTS PTT and VENTS PVK series.
VENTS
3. If the noise is a major concern, consider using acoustic flexible round
ducting (VENTS ISOVENT insulated flexible ducting series). This can remove up to about a third of the noise generated by air turbulence. It’s
necessary to use at least one metre on both ends of the fan to get the full
benefits. Using noise silencers, either rigid (VENTS SR series) or flexible
(VENTS SRF or VENTS SRP series) is also a good way to reduce the noise
(Fig.15). They can make it possible to run a ventilation system in a small
domestic setting. Again, for full effect, fix a silencer on each end of your
fan. This will help to reduce noise levels by up to a third.
VENTS
VENTS
VENTS
VENTS
Fig. 15. Use of silencers (VENTS SR, SRF or SRP) and acoustic ducts (VENTS
Isovent) considerably reduces the noise caused by airflow in ventilation
system.
VENTS
Fig. 13. Exhaust fan is to be installed diagonally opposite the intake fan for
better airflow and hot&humid air removal.
4. To achieve accurate climate control in hot and cold weather it’s worth
using fans with built-in automatic speed control module with built into
the fan’s duct temperature sensor (VENTS TT...U series and VENTS VK...U
series) or with remote 4 m length temperature sensor (VENTS TT...Un series and VENTS VK...Un series) (Fig.16). Regular air changes are critical for
good growth. A combined integrated speed control and thermostat will
allow you to regulate the number of air changes per hour. It’ll also com-
7
pensate for hot and cold weather by increasing or decreasing the air flow
if necessary. Fans will run at a reduced speed continuously, only switching
to full speed when triggered by the temperature sensor.
VENTS
VENTS
VENTS
VENTS
VENTS
VENTS
Fig. 17. Heat generating equipments must be stored outside the growroom.
VENTS
VENTS
Fig. 16. Use intake fan VENTS TT...U and exhaust fan VENTS VK...U with
speed and temperature control module to achieve better temperature
and air quality conditions.
5. To ensure electrical safety and avoid unnecessary heat transfer, any
equipment that generates heat should to be stored outside the grow room,
on a shelf or any non-flammable surface (Fig.17-18).
Fig. 18. Nutrient reservoir, any liquid nutrients, fertilizers and additives
should also be outside your grow room.
Following the above principles you can construct an effective budget indoor garden yourself,
suited around you, while creating the ideal environment for your plants.
All you need to do after is to choose a method to grow your plants: whether it’s growing passively in plant pots, or using an active hydroponics system – all will flourish in your well planned
indoor garden.
We wish you good luck!
With best wishes,
VENTS team
8